Materials with an extremely low thermal and high electrical conductivity that are easy to process, foldable, and nonflammable are required for sustainable applications, notably in energy converters, miniaturized electronics, and high-temperature fuel cells. Given the inherent correlation between high thermal and high electrical conductivity, innovative design concepts that decouple phonon and electron transport are necessary. We achieved this unique combination of thermal conductivity 19.8 ± 7.8 mW/m/K (cross-plane) and 31.8 ± 11.8 mW/m/K (in-plane); electrical conductivity 4.2 S/cm in-plane in electrospun nonwovens comprising carbon as the matrix and silicon-based ceramics as nano-sized inclusions with a sea-island nanostructure. The carbon phase modulates electronic transport for high electrical conductivity, and the ceramic phase induces phonon scattering for low thermal conductivity by excessive boundary scattering. Our strategy can be used to fabricate the unique nonwoven materials for real-world applications and will inspire the design of materials made from carbon and ceramic.

Water resources are shrinking year by year, and fog water collectors (FWCs) are already being used in humid regions, where populations have limited access to traditional water resources. The aim of...

Sponges based on short electrospun fibers have received significant attention due to their ultrahigh porosity, lightweight, and multifunctional characteristics. In particular, polyimide (PI) sponges have been researched due to their exceptional mechanical properties and thermal stability. Nevertheless, a number of sponges, including PI, are usually hydrophobic and synthesized in toxic, nonwater solvents (e.g., 1,4-dioxane). Conversely, hydrophilic sponges disintegrate upon contact with water. Here, we suggest a new strategy to fabricate PI sponges in water by introducing a suitable surfactant, sodium dodecylbenzenesulfonate (SDBS) (sPI sponges). With less than 1 wt % of SDBS with respect to PI short fibers, they can be homogeneously dispersed in water and mixed well with poly(amic acid) (PAA) solution. The synthesized sponge, depending on the concentration of SDBS, showed hydrophilic properties and substantial water uptake above 5000%. The hydrophilic properties of the sponges, which are not common, and the preparation from aqueous solution introduce new research opportunities. Such hydrophilic sponges are particularly special because they do not swell in contact with water, which makes them dimensionally stable. The methods presented here can serve as a milestone for the future development of various kinds of hydrophilic sponges applied for various applications, ranging from tissue engineering to oil/water separation.

For the last two decades, nanostructured carbon materials have attracted significant attention, as they exhibit unusual physicochemical properties different from their bulk counterpart. Nevertheless, agglomeration and re-stacking of carbon nanostructures have always limited optimal performance, with larger loading amount. To solve this issue, porous and compressible carbon-based sponges have been researched, but most of the previously suggested carbon foams were either not very porous, synthesized at high temperature heat treatment, and/or not applicable for carbon nanoparticles. In this work, we have successfully fabricated ultra-porous (porosity about 98-99%), polyimide-carbon nanoparticle (PI-C) composites by combining Ketjen black nanoparticles with PI short fibers, by simple freeze-drying and subsequent heat treatments at low temperature (240 degrees C). Based on the analysis, it has been discovered that the fabricated PI-C sponges not only exhibit highly robust mechanical properties but also retain low thermal conductivity even in comparison with pristine PI sponges. This work provides a milestone in fabricating a number of C-electrospun polymeric sponges by freeze drying and subsequent heat treatments, which are expected to be utilized in various fields of research. (C) 2019 Published by Elsevier Ltd.